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Human population has been growing exponentially since very early on
How early on? Seven billion is just 32 exponential doublings since Adam and Eve. Accepting the Biblical 6000 years, the populations must be growing at a meager 0.38% annual rate. (Wanna assume total K millenia? Take the K-th root 1.023, or roughly divide 2.3% by K.) Since when the humanity broke away from bio-economic limitations for primates?

The industrial evolution rate change was clear, indeed. Perhaps most populations were growing at >1% rate most of the time - but the "exceptional" setbacks are parts of the game, and their probability increases with the population number approaching habitat limitations. As for the modern demographic transition... I would not take it for granted. It is hard to delineate how much emancipation, austerities are natural or labored.

by das monde on Thu Jul 2nd, 2015 at 06:29:26 AM EST
[ Parent ]
(Wanna assume total K millenia? Take the K-th root 1.023, or roughly divide 2.3% by K.)

That's still exponential growth ... since from at the very latest the second diaspora from Africa (as its conceivable that the first diaspora along the southern Asian coasts to Australia was more or less linear growth).

Its not logistic growth if keeps on growing at a growing rate. Since, evidently, logistic growth at a ceiling population that falls short of the population to fill up Africa, Eurasia and the Americas at a hunter gatherer density would have left big chunks of one or more continents empty of humans ... as we see big chunks of multiple continents empty of pretty much any other single species of primate.

Its not logistic growth with a ceiling at hunter gatherer densities worldwide if the growth continues to lead to population densities that require the additional work of settled agriculture.

Discussing how many doublings its been since what some evidence, including genetic evidence, suggests was passage through a demographic bottleneck in southern Africa is not disputing whether or not its exponential growth ... its only about estimating the exponential rate.

As far as demographic transition ... I deliberately phrased it as a potential, rather than a certainty. Its hard to sit writing in Beijing, now at twice the population of my home state of Ohio and still growing, and take it as a certainty.


I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.

by BruceMcF (agila61 at netscape dot net) on Thu Jul 2nd, 2015 at 06:47:06 AM EST
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BruceMcF:
Its hard to sit writing in Beijing, now at twice the population of my home state of Ohio and still growing, and take it as a certainty.

According to Rosling, China is at its peak. What is more, it has a 200 million decline in the pipeline as larger generations die and smaller are born.

Beijing will probably keep growing though, I think capital size is mostly a reflection of concentration of power.

by fjallstrom on Thu Jul 2nd, 2015 at 03:16:14 PM EST
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Its at a peak, which is going to cause a "restucturing" in many sectors, including the University sector (just read a China Daily article about Tsinghua and Peking University trying to steal each other's top applicants) ...
... but my comment was not regarding current trends and projections, but regarding how certain we can be about how closely the outcome will follow the projection. There are quite a large number of one child families with the child born when the mother is relatively young, and so over the coming decade a Baby Boom of fairly impressive absolute magnitude is feasible, even if social norms lean against it at present.

I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
by BruceMcF (agila61 at netscape dot net) on Thu Jul 2nd, 2015 at 10:08:55 PM EST
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The exceptional feature of humans is that they are apt to expand their resource base gradually or frequently. The industrial revolution is just the most momentous example. That allows humans to keep their "exponential" growth rate almost continuously. However, I would be interested to correlate the growth rate fluctuations  with resource "revolutions" and overshots, rises and falls of civilization centers. How direct are estimates of, say, the population estimates of the imperial Rome? Could we detect any demographic transitions then?  
by das monde on Thu Jul 2nd, 2015 at 09:59:52 PM EST
[ Parent ]
World population estimates, according to Livi-Bacci, A concise history of world populations:

10,000 BC - 6 millions
400 BC - 153 millions
0 - 252 millions
200 - 257
600 - 208 (Justinian plague)
1000 - 253
1200 - 400
1340 - 442
1400 - 375 (Black plague)
1500 - 461
1600 - 578
1700 - 680
1750 - 771
1800 - 954
1850 - 1241
1900 - 1634
1950 - 2520
2000 - 6236

das monde:

Perhaps most populations were growing at >1% rate most of the time

Looks that way, yes.

das monde:

but the "exceptional" setbacks are parts of the game, and their probability increases with the population number approaching habitat limitations

But it is not planned or genetic.

by fjallstrom on Thu Jul 2nd, 2015 at 03:14:18 PM EST
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How evidence-direct are the estimates?

Let's translate the numbers into implied doubling periods:
10000 BC - 400 BC: 2055 years;
400 BC - 0: 556 years;
0 - 200: 7056 years;
200 - 600: minus 1311 years ("decay");
600 - 1000: 1416 years;
1000 - 1200: 303 years;
1200 - 1340: 972 years;
1340 - 1400: minus 253 years;
1400 - 1500: 336 years;
1500 - 1600: 306 years;
1600 - 1700: 427 years;
1700 - 1750: 276 years;
1750 - 1800: 163 years;
1800 - 1850: 132 years;
1850 - 1900: 126 years;
1900 - 1950: 80 years;
1950 - 2000: 38 years.

That is a wild variation. And the industrial "singularity" is staggering, isn't it?

For comparison, the implied biblical doubling period is about 190 years.

by das monde on Thu Jul 2nd, 2015 at 10:11:00 PM EST
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Post-1500 that's a stable superexponential trend. Prior to that, the resolution is too poor to distinguish between an exponential and a superexponential trend.

I cannot prove, but would not be surprised to find, that a large part of the superexponentiality of the post-1500 is simply an artifact of more fine-meshed census efforts. Getting better at counting almost always means you find more of what you are counting.

- Jake

Friends come and go. Enemies accumulate.

by JakeS (JangoSierra 'at' gmail 'dot' com) on Fri Jul 3rd, 2015 at 03:56:19 AM EST
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das monde:
How evidence-direct are the estimates?

Livi-Bacci gets the numbers (except 1950 and 2000, those are from the UN) from Essai sur l'évolution du nombre des hommes on JSTOR.

by fjallstrom on Fri Jul 3rd, 2015 at 05:24:40 AM EST
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